Hi lilyimportwholes,
It's great to see you're using QuickBooks Online's powerful inventory management features to their full potential. Purchase orders are the best way to streamline bill creation, as they allow you to easily record the inventory purchase on a future date. The behaviour you're describing is normal, and appears to be working as designed. I'll be happy to go over how inventory and cost of goods sold are handled in QuickBooks Online.
Traditionally, inventory management has required complex transactions to record the value of the asset, as well as the expense portion. QuickBooks Online makes this simple by keeping track of the asset, and automatically deducting your costs of goods sold once the item is sold based on the FIFO method. Each bill you create using the Item details section for inventory products is handled this way. Purchasing inventory can be seen as converting cash into a different asset, the expense is incurred once that item is sold. To make sure your items are set up correctly, simply head to your Gear icon then select Products and Services. Click Edit for any item to confirm the Inventory asset account, Income account, and the Expense account.
Your accountant is an incredible resource for help sorting out inventory. You can easily invite your accountant as a user to approach this together. To search for a pro in your area, simply head to the My Accountant tab in QuickBooks Online then click on Find a pro to help.
Let me know if there's anything else I can help you with!
